The present invention relates generally to switching voltage regulators, and more particularly, to methods and systems for pulse width modulated switching voltage regulators.
Voltage regulators perform the important function of providing a constant voltage level. The voltage level can then be used as a reference or for powering devices in a repeatable, reliable manner of operation. By way of example, a regulated 5 volts DC can be used as a logical 1 reference value with a ground or 0 volts DC being a logical 0 reference. Similarly, a regulated 5 volts DC can be used to cause a transistor to switch at a repeatable switching speed. Increasing the voltage to greater than 5 volts DC may decrease the time required for the transistor to switch (e.g., increase the switching speed) but may also damage the transistor. Decreasing the voltage to less than 5 volts DC may increase the time required for the transistor to switch (e.g., decrease the switching speed) or prevent the transistor from switching at all. Further, a voltage less than 5 volts DC may or may not be sufficient to be detected as a logical 1 reference and instead may be erroneously interpreted as a logical 0.
As semiconductor device (e.g., transistors, transistor gates and channels, capacitors, resistors, line widths, etc.) sizes have decreased, the operating voltages have also decreased. As a result, the operating voltages have been reduced from 5 volts to a low are 3.3 volts and even 1.1 volts DC. As the operating voltage has been reduced, the operating voltage regulation requirements have become ever more strict. As a result, the regulated operating voltage must be maintained within a narrower voltage tolerance.
Linear regulator circuits are relatively power inefficient as compared to a typical pulse width modulated switching regulator circuit. Increased power efficiency is also a constant demand corresponding with shrinking semiconductor device sizes.
Unfortunately, typical pulse width modulated switching regulator circuits can allow the regulated voltage output to dip or rise outside an acceptable output voltage range between modulation pulses. The undesirable output voltage dips or rises are typically due to transient circuit loads having a frequency greater than the pulse width modulating frequency. The undesirable output voltage dips or rises can cause data errors and can result in inconsistent circuit operations of the circuits driven by the output voltage. There is a need for an improved pulse width modulated switching regulator circuit that compensates for higher frequency transient loads without substantially affecting the power efficiency of the pulse width modulated switching regulator circuit.